Both local knowledge and hands-on experience are valuable in coastal navigation, however, they do not substitute for professional education. The skipper of the FRASERKING navigated the tug along the coast using his local knowledge. He did not use the aids to navigation which were available to him. For more than eight hours after departing from Port Hardy he did not look at the compass nor did he plot the tug's position on the chart. Only when the radar began to malfunction and the skipper was not sure of the tug's location, did he begin to use the magnetic compass and unpack and use the GPS receiver. After unpacking and switching on the GPS in the wheelhouse the skipper took the first readout that appeared on its screen as the tug's position. Without plotting it on the chart, he transmitted the coordinates to MCTS. These coordinates were subsequently re-transmitted by MCTS to alert and direct other vessels. It is most probable that the metal wheelhouse bulkheads shielded the GPS antennae from the satellite radio signal. When he moved the instrument out of the wheelhouse it began to work properly. By this time, however, the tug and tow was more than 20 miles from the tug's last verified position and had entered the waters of Kildidt Sound. Apparently, from the last known position off Dugout Rocks the tug and tow had proceeded west of Calvert Island although the skipper had intended to enter Fitz Hugh Sound, east of the island. Once the skipper obtained more accurate readings from the GPS, he was able to find the tug's position on the aeronautical chart which had been supplied by the helicopter. Because aeronautical charts do not show depths of water, they are of little use for marine navigation. The tug was manoeuvring in close proximity to many rocks, shallow spots and underwater pinnacles, which were not marked on the chart, and the barge grounded. The barge refloated on the rising tide. The sea bottom in Kildidt Sound, like the nearby land, is rocky therefore it is almost certain that the barge sustained damage to its shell plating while it was aground. Its watertight integrity was affected, consequently, although it refloated it was also taking on water. The ingress of water caused a list and gradually decreased the barge's freeboard until it sank some fifteen hours later.Analysis Both local knowledge and hands-on experience are valuable in coastal navigation, however, they do not substitute for professional education. The skipper of the FRASERKING navigated the tug along the coast using his local knowledge. He did not use the aids to navigation which were available to him. For more than eight hours after departing from Port Hardy he did not look at the compass nor did he plot the tug's position on the chart. Only when the radar began to malfunction and the skipper was not sure of the tug's location, did he begin to use the magnetic compass and unpack and use the GPS receiver. After unpacking and switching on the GPS in the wheelhouse the skipper took the first readout that appeared on its screen as the tug's position. Without plotting it on the chart, he transmitted the coordinates to MCTS. These coordinates were subsequently re-transmitted by MCTS to alert and direct other vessels. It is most probable that the metal wheelhouse bulkheads shielded the GPS antennae from the satellite radio signal. When he moved the instrument out of the wheelhouse it began to work properly. By this time, however, the tug and tow was more than 20 miles from the tug's last verified position and had entered the waters of Kildidt Sound. Apparently, from the last known position off Dugout Rocks the tug and tow had proceeded west of Calvert Island although the skipper had intended to enter Fitz Hugh Sound, east of the island. Once the skipper obtained more accurate readings from the GPS, he was able to find the tug's position on the aeronautical chart which had been supplied by the helicopter. Because aeronautical charts do not show depths of water, they are of little use for marine navigation. The tug was manoeuvring in close proximity to many rocks, shallow spots and underwater pinnacles, which were not marked on the chart, and the barge grounded. The barge refloated on the rising tide. The sea bottom in Kildidt Sound, like the nearby land, is rocky therefore it is almost certain that the barge sustained damage to its shell plating while it was aground. Its watertight integrity was affected, consequently, although it refloated it was also taking on water. The ingress of water caused a list and gradually decreased the barge's freeboard until it sank some fifteen hours later. The tug was navigated by local knowledge and by radar. The tug's positions and intended courses were not marked on the chart. The tug was not equipped with charts covering the waters other than those the skipper intended to transit. Only when the radar began to malfunction and the skipper became disoriented did he attempt to use the compass and to unpack and use the hand-held GPS receiver. The signals to the hand-held GPS receiver in the wheel-house were most probably affected by the vessel's steel structure and the skipper gave an incorrect position to SAR when he requested help. SAR units located the tug and barge some 23 miles from the location the skipper first reported. The aeronautical charts provided to the tug by the SAR helicopter were of limited utility. The barge grounded on a rocky bottom during a falling tide and sustained damage to its shell plating. The barge was left aground when the skipper of the tug decided to seek shelter for his vessel for the night. The barge floated free on a rising tide but was taking water through the damaged hull. When again under tow, the barge sank in a depth of water of approximately 45 m. When again under tow, the barge sank in a depth of water of approximately 45 m.Findings The tug was navigated by local knowledge and by radar. The tug's positions and intended courses were not marked on the chart. The tug was not equipped with charts covering the waters other than those the skipper intended to transit. Only when the radar began to malfunction and the skipper became disoriented did he attempt to use the compass and to unpack and use the hand-held GPS receiver. The signals to the hand-held GPS receiver in the wheel-house were most probably affected by the vessel's steel structure and the skipper gave an incorrect position to SAR when he requested help. SAR units located the tug and barge some 23 miles from the location the skipper first reported. The aeronautical charts provided to the tug by the SAR helicopter were of limited utility. The barge grounded on a rocky bottom during a falling tide and sustained damage to its shell plating. The barge was left aground when the skipper of the tug decided to seek shelter for his vessel for the night. The barge floated free on a rising tide but was taking water through the damaged hull. When again under tow, the barge sank in a depth of water of approximately 45 m. When again under tow, the barge sank in a depth of water of approximately 45 m. The barge D.H.T. No 3 ran aground and subsequently sank with its cargo in Kildidt Sound because the skipper/owner of the FRASERKING did not make effective use of the aids to navigation on board but relied almost entirely on the radar for navigation. After the radar broke down, the skipper became disoriented, the tug deviated from its planned route and entered waters for which the tug did not have charts. The aeronautical charts provided to the tug by the SAR helicopter did not show depths or dangers and were of limited utility. The barge sank because its shell plating was damaged when it ran aground.Causes and Contributing Factors The barge D.H.T. No 3 ran aground and subsequently sank with its cargo in Kildidt Sound because the skipper/owner of the FRASERKING did not make effective use of the aids to navigation on board but relied almost entirely on the radar for navigation. After the radar broke down, the skipper became disoriented, the tug deviated from its planned route and entered waters for which the tug did not have charts. The aeronautical charts provided to the tug by the SAR helicopter did not show depths or dangers and were of limited utility. The barge sank because its shell plating was damaged when it ran aground.